Michael Grimm did bad things. But others are doing worse and are still getting away with it.

Grimm is the former Republican congressman from New York who was caught cheating on his taxes — sales and employee taxes for a health food business he once owned. The case was a cause célèbre just a few months ago and caused Grimm, a former Marine and FBI agent, to resign from office.

He deserves to be an ex-congressman. One liar and cheater fewer in Washington is a good thing. And Grimm may even spend a few days in jail to see how it feels.

Grimm has agreed to a plea deal and — although he hasn’t been sentenced yet — full details of his crime were recently revealed by federal prosecutors for the Eastern District of New York.

“From 2007 to 2010 Michael Grimm under-reported to federal and state tax authorities the true amount of money [his company] Healthalicious earned and used a portion of the restaurant’s unreported receipts to pay the restaurant’s employees’ wages off the books,” prosecutors alleged.

Some of the employees were also not eligible to legally work in the US. Naturally, false tax returns were filed. Grimm was said to have concealed more than $900,000 in gross receipts from his own accountant.

And New York state lost between $80,000 and $200,000 in tax revenue because of this scheme.

What’s missing is a description of how Grimm pulled this off. Was it a sophisticated plot or just an old-fashioned off-the-top skim?

A source close to the case tells me that the 45-year-old Grimm was simply pocketing money. He wasn’t using any sophisticated technology that might have permitted him to actually get away with this crime.

But I’m concerned about those who are cheating via high tech. A lot of stores and restaurants in New York are using point-of-sale terminals, the latest in computer/cash registers that make sales (and sales tax) disappear. California and a bunch of other states have already cracked down on these “zapper” registers.

Despite my years of prodding, New York hasn’t.

The prosecutors in Brooklyn who snagged Grimm are welcome to give me a call. I’ll put them on the trail of zapper tax cheats a lot bigger than Grimm. If there was even a half-hearted effort at sales-tax enforcement, New York could get billions more in revenue each year.

Grimm’s a start. But the state needs to make other crooked shopkeepers feel a lot grimmer if it really cares about snagging all the money it is owed.

Another person was fired a couple of months ago by the Philadelphia region of the Census Bureau for not following procedure — essentially cutting corners during the interview process in surveys on the unemployment rate and other economic data.

As I’ve been telling you, a lot of cheating has been going on. The most blatant case happened in the Philly region and involved a survey taker named Julius Buckmon. That case led to a congressional investigation that was prompted by The Post’s reporting.

Because the disciplinary process is so secretive, there’s no way of knowing how many Census takers have been fired or punished for manipulating data. Whistle-blowers in five of the six Census regions have told me that cheating is widespread. And all those whistle-blowers have volunteered to tell what they know to investigators.

I’m glad Census is getting tough. What it should do at this point, however, is grant amnesty to those who have cut corners (but haven’t completely fabricated surveys) so agencies like the Labor Department and the Justice Department can determine how misleading their data really are.

Lax supervision is largely responsible for cheating. And the supervisors are the ones who aren’t being punished.

Now, on a lighter note about a different bad habit:

McDonald’s has come up with a new marketing gimmick — and I use the word “gimmick” affectionately — that started the day after the Super Bowl.

Selected customers will get to “pay” for their meal simply by saying something nice. It’s called “Pay for Lovin’.” (No, wait, that sounds like a different kind of business!)

Here’s how it works. If you are picked, you can get your meal for free by, say, calling your mom and telling her you love her. Mom dead? No problem. McDonald’s will let you do a jig for your food or hug your kid.

Look, I agree, it’s a bit corny. And there are so many possibilities that a trained brain like mine can come up with.

For example, make customers go up to total strangers and plant a kiss on their cheek. Too much? How about giving a stranger a simple compliment: “That child with you is so beautiful. Is she yours or did you borrow her because you were too embarrassed to order a Happy Meal for yourself?”

But I have a better idea that any burger chain or fancy restaurant is welcome to use if it pays me enough. It’s called “Singin’ for Your Supper.” Random customers have to step up to a karaoke machine and belt out a tune.

If the people don’t like it, the punishment is that the singer has to eat a second free burger.